1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display with a light shutter and a method for driving the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for improving a display quality by eliminating a motion-blurring.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) of an active matrix driving system uses a thin film transistor (TFT) as a switching device to display a moving picture. Since such an LCD can be fabricated into a smaller device than a conventional cathode ray tube (CRT), it has been widely used for a monitor for a personal computer or a notebook computer as well as office automation equipment such as a copy machine, etc. and portable equipment such as a cellular phone and a pager, etc.
However, the liquid crystal display has a problem of a motion-blurring that causes an overlapped or blurred field in a moving picture due to a response characteristic of a liquid crystal and a data delay. This will be described in conjunction with FIG. 1A and FIG. 1B representing data characteristics of a CRT and an LCD.
When the CRT and the LCD are operated at 60 Hz, one field period is approximately 16.7 ms corresponding to 1/60 second. The CRT radiates a fluorescent body only during an initial very short time of the one field period to display data while remaining at a pause interval during almost all other portions of the one field period as shown in FIG. 1A. Accordingly, an observer sees a display image of the CRT similar to a real image as shown in FIG. 1C without generating a motion-blurring from a moving picture.
On the other hand, in the liquid crystal display, as shown in FIG. 2, data are applied to a liquid crystal in a scanning interval supplied with a gate high voltage Vgh and data applied to the liquid crystal are maintained in a non-scanning interval that is a major portion of the one field period. Accordingly, the liquid crystal display generates a motion-blurring in a moving picture because each liquid crystal continuously displays an image without a pause interval during the one field period.
Recently, there has been an effort to include a pause interval in the liquid crystal display device similar to the CRT so as to reduce a motion-blurring in the liquid crystal display.
For instance, IBM corporation has suggested the scheme of blinking a backlight radiating continuously during the one field period as shown in FIG. 3B. However, this scheme has a problem yet to be resolved. Although the blinking of the backlight permits the pause interval corresponding to the time interval when the backlight is turned off as shown in FIG. 4 to reduce a motion-blurring, an additional control circuit for driving the backlight and a modification of the driving circuit are required. Moreover, brightness is more deteriorated in the direct current driving.
Sharp corporation has suggested the scheme of modulating an existent data having only a polarity inversion as shown in FIG. 5A into data shown in FIG. 5B to assign a time interval when data do not exist in one field period. This scheme allows black data having no data, so that no voltage is applied to the liquid crystal cell in a normally black mode liquid crystal display to include a pause interval within the one field period. However, such a method creates another problem in that a driving frequency according to a data on/off should be increased, for example, from 60 Hz to 120 Hz. As a result, a timing controller and a data driving circuit should be modified to reduce a data charge time in a high resolution.